The embodiments herein relate generally to the preparation of anorganic substances from bovine bone. In particular, this invention relates to the preparation of natural hydroxyapatite granules with the high specific surface area, the low crude protein content, the multiple pore size, and the high total volumetric porosity using chemical treatment and annealing process with extremely low heating rate at low temperature.
The use of bone grafts in cranio-maxillofacial and dental surgery is growing increasingly. The autografts and the allografts are very effective as bone grafting substitute due to essential physicochemical and biological properties such as their immune response, good osteoinductivity, and osteoconductivity. However, due to the disadvantage of limited supply and availability, alternative biomaterials such as xenografts, which is animal derived source of bone graft or synthetic bone grafts have been proposed and intensively studied.
Specially, among these, the origin of bovine bone grafts has practically unlimited availability and has good physicochemical and structure similar to human bone. Natural hydroxyapatite extracted from bovine bone is almost biocompatible to the human bone due to the properties of osteoconductivity. However, altering the natural structure of hydroxyapatite such as microstructure and pore structure by use of higher temperature can have a negative impact on the physicochemical characterization. This may not be the optimum model to maximize bioresorption and bioactivity. It may also minimize the bone regeneration and healing. Embodiments of the disclosed invention solve these problems. The prior art includes: U.S. Pat. No. 8,298,566 issued to Markoulides; U.S. Pat. No. 5,167,961 issued to Geistlich; and U.S. Pat. No. 2,968,593 issued to Espkin.
Markoulides teaches a process of extracting natural hydroxyapatite from bovine bone comprising: soaking bovine bone in hydrogen peroxide for greater than 20 hours to produce granules with a typical specific surface are of 100 m2/g. Geistlich teaches a process of extracting natural hydroxyapatite from bovine bone comprising: soaking bovine bone in ammonia for 2 to 200 hours to produce granules with a specific surface of, preferably, 120 m2/g while heat increases from 100 to 350 degrees centigrade. Espkin uses a lower temperature range. However, none of these processes teach washing the bone fragments in deionized water which provides a substantial improvement in the invention described below.